The transition to kindergarten is one of the most impactful transitions in the life of a young child, requiring new social, emotional, and cognitive competencies across a variety of domains and an emphasis on formal instruction and evaluation never experienced before. For many children in full-time kindergarten, kindergarten now functions as the new first grade, and the social and academic competencies observed during this time set the stage for later school success. Unfortunately, although many children make successful transitions to school, some do not. School adjustment is multi-faceted and, not surprisingly, multiply determined. However, one particular determinant, child sleep, is largely understudied as a predictor of early school success, despite growing evidence that sleep problems in children and adults predict externalizing and internalizing behavior problems, emotion dysregulation, sleepiness, and attentional difficulties during daytime hours. The present study draws upon work by the principal investigator and others in his investigative team and focuses on the unique role of sleep in young children in predicting children's adjustment across the kindergarten year, and the role of parenting in shaping good sleep habits in young children during this transition. We make use of an innovative measurement-burst design to assess child sleep (quality, duration, and lability), parenting, and coparenting and personal distress as predictors of child sleep characteristics, with assessments obtained before kindergarten begins (pre-K), early in the transition year (late September-early October), mid-transition (November), and late- transition (April). Children's learning engagement, academic progress, socio-emotional functioning, executive functioning, and literacy skills will be assessed at early-, mid-, and late-transition timepoints. Analyses will focus on trajectories of child sleep as predictors of school adjustment, and parenting and couple distress as predictors of child sleep across the kindergarten year. This research will provide an important foundation for understanding the role of children's sleep in predicting children's transition to K across the full year of school, and th role of parenting and parental distress in shaping children's sleep during this pivotal time.